Fig. 6.

Metformin inhibits tumor growth in an RPMI8266 xenograft mouse model. a NOD/SCID mice received metformin or PBS by oral gavage every day after subcutaneous implantation of RPMI8226 cells. Tumor sizes were monitored every 3 days. b Body weight of mice was monitored every 3 days. c Immunohistochemical analysis of tumors from the metformin and control groups showing upregulation of AMPK and downregulation of mTOR and Ki-67. Expression levels were scored semi- quantitatively as the percentage of positive cells according to the following system: +,< 25%; ++, 25%–49%; +++, 50%–74%; ++++, 75%–100%. All data are expressed as mean ± SD of values from triplicate experiments. *P < 0.05, **P < 0.01 compared with the control group